A light emitting diode (LED) is a compound semiconductor device that converts electric energy into light energy, and various colors can be realized by controlling a composition ratio of the compound semiconductor.
Nitride semiconductor LEDs have advantages of low power consumption, a semi-permanent lifetime, a fast response time, safety, and environment friendliness when compared to conventional light sources such as fluorescent lamps and incandescent lamps. Accordingly, application of the nitride semiconductor LED has expanded to being applied as an LED backlight replacing a cold cathode fluorescent lamp (CCFL) that configures a backlight of a liquid crystal display (LCD) device, a white LED lighting device capable of replacing a fluorescent lamp or an incandescent lamp, a headlight of a vehicle, and traffic lights.
However, white light from an LED has a problem in that a color rendering index (CRI) thereof is insufficient. To resolve such a problem, a fluorescent substance excited at various wavelengths should be used.